Current studies are focused on phytanic acid storage disease and Niemann-Pick Disease. Cell culture studies have revealed a case with accumulation of phytanic acid in plasma but with only moderately defective oxidation of phytenate in cell culture. Previously studied homozygotes have oxidized phytanate at less than 5% the control rate; cells from the patient under study oxidize at almost half the normal rate. Another possible variant form of the disease is under study in which two siblings showed grossly impaired growth and neurologic development. The cell culture studies show a 90% defect in phytanate oxidation. The basis for the different phenotypic expression is under study. Attempts are being made to find a more acceptable therapeutic dietary regimen. The metabolic fate of phytanate in cultured cells is being studied in control and mutant cells. Accumulation of bis(monacylglyceryl) phosphate has been noted in patients with Niemann-Pick Disease. The pathway for formation of this compound is under study in normal liver subcellular particles. An animal model in which bis(monoacylglyceryl) phosphate accumulates has been developed utlizing triparanol-treated rats. The relationship of this compound to the underlying pathogenesis of Niemann-Pick Disease is under investigation. BIBLIOGRAPHIC REFERENCES: Poorthuis, B.J.H.M. and K.Y. Hostetler. J. Biol. Chem. 250:3293-3302, 1975. Hostetler, K.Y., J. Galesloot, P. Boer and H. van den Bosch. Biochim. Biophys. Acta. 380:382-389, 1975.